We use this simple rule of thumb: If you are working with a person multiple times a week, this individual should be giving you feedback. Do not include people that you simply see and talk to — that is not enough. For example, do not include your receptionist or your cubicle neighbor. Yes, you talk to them, but you don’t really work with them. They won’t provide the insight you are looking for.
We recommend having 5-10 feedback providers in your feedback network. It is better to have too many than too few. Also, keep in mind you can change your feedback circle at any time.